Optic Nerve Sheath Diameter in Retrobulbar Ultrasound as a Surrogate Measure for Intracranial Pressure Before and After Non-invasive Strategies

The ONSD in each eye was measured vertically and horizontally 3 mm behind the optic disc, with the two values averaged. No pressure was applied to the orbit. At each time point, measurements were taken within 5 min. The measurements were made before (T1) and after some of the strategies according to group 30 min (T2), 60 min (T3), and 90 min (T4).